The present invention relates to a binocular observation instrument of the variety in which the two tubes which contain the optical elements are connected with each other by a connecting bridge having a pivot pin for adjustment of the pupil distance.
Telescopes are known in which two individual telescopes are connected with each other by a single-pivot or double-pivot connecting bridge. The pivot axes are arranged parallel to the optical axes of the individual telescopes and make possible an adjustment of the pupil distance and a compact folding together of the telescope. In accordance with their design and development, telescopes are intended only for the observation of remote objects but not for viewing objects within working distance.
It is also already known from German Pat. No. 2,622,743 to arrange in front of the telescope a system which consists of supplementary lenses and deflecting means and thereby to expand the telescope into a microscope. Such a supplementary system is a separate structural part and as such is relatively expensive and not always at hand.
For very fine work in which the article to be worked is located within the working range and must be observed magnified, so-called binocular magnifiers are known. They consist of two tubes which contain the optical elements and are customarily cemented onto the eyeglasses of the observer arranged in an eyeglass frame. The pupil distance is in this case invariable and adapted to the observer, as is true also of the angle of convergence .alpha. between the optical axes of the tubes.
From U.S. Pat. No. 3,029,696, there is known a binocular magnifier in which the two tubes are so connected with an eyeglass frame that the pupil distance is adjustable by shifting the tubes in opposite directions along a straight line. This displacement is effected by actuating a central adjustable member. By means of the same adjustment member, adjustment of the angle of convergence .alpha. is also possible. In this case, each change in the pupil distance requires a readjustment of the angle of convergence .alpha.. Furthermore, the levers and gears necessary for transmitting the adjustment movements to the tubes make these binocular magnifiers expensive and heavy.